Insole for an Item of Footwear and an Item of Footwear Comprising the Same

ABSTRACT

A shoe has a sole, at least a portion of the sole of the shoe comprising a compressible material, the material being such that the application of a pressure above a threshold pressure causes the electrical conductivity of the material to change. There is also provided a shoe comprising a sole; a display means operable by the wearer of the shoe to provide a display on the exterior surface of the shoe; wherein the sole of the shoe comprises a compressible material, the material being such that the application of pressure causes the electrical conductivity of the material to change, whereby the display means may be controlled by the application of pressure to the compressible material in the sole of the shoe. An insole for use in a shoe is also disclosed, the insole comprising a compressible material, the material being such that the application of a pressure above a threshold pressure causes the electrical conductivity of the material to change.

BACKGROUND OF THE INVENTION

The present invention relates to an insole and sole construction for an item of footwear and to an item of footwear comprising the same.

It is established practice to adorn the exterior of shoes with patterns and markings. The present specification will refer to ‘shoe’ or ‘shoes’ in relation to the invention. However, this is to be understood as embracing all forms of footwear, including but not limited to shoes, training shoes, sports shoes, such as running shoes and soccer boots, golf shoes, sandals, boots, plimsolls, slippers and the like. Other items of footwear embraced by these terms including roller skates, ice skates, ski and snowboard boots and other sporting footwear. The terms ‘shoe’ and ‘shoes’ are used herein as a reference to this generic group of footwear items, unless otherwise specified.

For some time considerable time, shoes, in particular those for infants and young children, have been provided with displays on their exterior incorporating lights, caused to flash on and off by the wearer of the shoe. The displays generally operate by way of a motion sensor, such that movement of the foot of the wearer triggers the lights to flash on and off in a prescribed pattern. Alternatively, the display may be activated by a device, such as a piezoelectric device, installed in the sole of the shoe and activated by the pressure of the sole of the foot of the wearer, as the shoe is being worn and the wearer walks or runs.

A significant advance in the technology of providing a visible and/or audible display on the exterior surface of a shoe is disclosed in WO 2005/020734. This document discloses, in one embodiment, an insole for a shoe having an extension member extending from the insole and a display device mounted to the extension member, such that when the insole is installed in a shoe the display device is supported on the exterior of the shoe providing a visible or audible display. The display device may be a self-contained device, providing a predetermined display according to a preset programme. In a preferred embodiment, the display device is controlled by a switch mounted in the insole and activated by the foot of the wearer while the shoe is being worn. WO 2005/020734 discloses using one or more arrays of pressure activated switches to control the display device.

Suitable pressure activated switches for use in the device of WO 2005/020734 are known. Typically, the switch comprises two contact members, one of which may be fixed and the second moveable, such that the application of pressure to the second contact member causes it to move into contact with the first contact member, thus completing an electrical circuit. The second contact member is typically biased to a position in which it does not contact the first contact member to hold the switch open, the pressure applied to the switch assembly acting against the biasing means to close the switch. While such switches have proven suitable for known display systems for shoes, the devices disclosed in WO 2005/020734 have been found to require an alternative design of switch, in order to realize the full potential of the concepts disclosed.

Accordingly, there is a need for an improved design of switch assembly for use in the soles of shoes and in insoles, such as those disclosed in WO 2005/020734.

SUMMARY OF THE INVENTION

In a first aspect, the present invention provides a shoe having a sole, at least a portion of the sole of the shoe comprising a compressible material, the material being such that the application of pressure causes the electrical conductivity of the material to change.

The compressible material is provided in at least a portion of the sole provides a pressure activated switch, operable by the wearer of the shoe by applying pressure with the appropriate part of their foot to the sole of the shoe. The switch may be employed to activate and/or otherwise control a range of devices, including a pedometer or the like. The shoe of this aspect of the present invention is particularly suitable for providing the control of a display means to provide a visible and/or audible display on the exterior of the shoe.

Accordingly, in a further aspect, the present invention provides a shoe comprising:

a sole;

a display means operable by the wearer of the shoe to provide a display on the exterior surface of the shoe;

wherein the sole of the shoe comprises a compressible material, the material being such that the application of pressure causes the electrical conductivity of the material to change, whereby the display means may be controlled by the application of pressure to the compressible material in the sole of the shoe.

The sole may have a single portion comprising the compressible material. Alternatively, the sole may have a plurality of discrete portions comprising the compressible material, thereby providing a plurality of discrete switch means within the sole. The plurality of discrete portions may be arranged to allow different parts of the wearer's foot to activate different functions. For example the wearer may be able to use one or more toes to activate or control a particular first function of the shoe, and the heel to control or activate a second function of the shoe. Further portions may be provided, for example to be activated by the instep, the ball of the foot, and the like. In a simple embodiment, the sole comprises a layer of compressible material across substantially its entire surface, such that pressure applied by the foot of the wearer to any significant portion of the sole will cause it to begin to conduct.

Suitable materials for use in the sole of the shoe of the present invention are known in the art. In one embodiment, the application of pressure to the material causes its electrical conductivity to change, for example increase. This increase in conductivity may used to control a device within the shoe, in particular the display devices mentioned hereinbefore. In an alternative embodiment, the material is one that is non-conducting in its rest state, that is without the application of pressure to the material. Once pressure above a certain threshold pressure is applied, the material becomes electrically conducting. In this way, the material may be used as a simple on/off switch, or by employing the changes in conductivity, in a more complex control system, in which variations in the pressure applied to the sole may be used as the mechanism for controlling the devices within the shoe.

The compressible material may comprise an insulating polymer matrix, in which is dispersed an electrically conducting filler, such as carbon or metal powders, including powders of nickel, copper, silver, aluminium and iron. Suitable carbon fillers include carbon nanotubes, carbon fibres, graphite, pyrolitic carbons and carbon blacks. A review of such materials suitable for inclusion in the sole of the shoe of the present invention is provided by Bloor, D. et al., ‘A metal-polymer composite with unusual properties’, J. Phys. D: Appl. Phys. 38 (2205) pages 2851 to 2860.

In one embodiment, the compressible material is a polymer composition that is elastically deformable from a quiescent state and comprising at least one electrically conductive filler dispersed within and encapsulated by a non-conductive elastomer. The nature and concentration of the filler is such that the electrical resistivity of the composition varies in response to an applied pressure. Such a compressible material is disclosed in WO 98/33193, the disclosure of which is incorporated herein by reference.

The compressible material used in the present invention may be of the type that an electrical current flows through the material, when under compression, by conduction through conductor particles brought into contact with one another. Alternatively, the compressible material may be a so-called quantum tunneling composite (QTC), in which the passage of electrons is believed to occur by means of tunneling between closely spaced conductor particles. Suitable QTC materials are known in the art and available commercially.

The conductive component of the filler is preferably selected from powder-form metallic elements and alloys, electrically conductive oxides of such elements and alloys, and mixtures thereof. Suitable electrically conductive materials for use as the fillers are metals, including titanium, tantalum, zirconium, vanadium, niobium, hafnium, aluminium, silicon, tin, chromium, molybdenum, tungsten, lead, manganese, beryllium, iron, cobalt, nickel, platinum, palladium, osmium, iridium, rhenium, technetium, rhodium, ruthenium, gold, silver, cadmium, copper, zinc, germanium, arsenic, antimony, bismuth, boron, scandium, as well as metals of the lanthanide and actinide series of the Periodic Table of the Elements. Preferred metals are nickel, titanium, zirconium and copper.

The conductive filler may be present as particles or powder of the conductive element or material. Alternatively, the filler may be in the form of a layer of the conducting element or material on a carrier core of powder, grains, fibres or other shaped forms. Alternatively, the conductive filler may be in the form of granules of the conductive element of material. In such a case, the granules are preferably in a size range of up to 2 mm, more preferably up to 1 mm in diameter, with a preferred size range being from 0.04 to 0.2 mm in diameter.

It is preferred that the conductive filler comprises particles of conductive material that are dendritic, filamentous or spiked in form, as these provide a compressible material with a greater sensitivity to the applied pressure. Preferably, the conductive filler particles have a spiky and/or dendritic surface texture, or a filamentary structure, with a three-dimensional chain-like network of spiky beads, with the chains having a cross-section of from 2 to 4 microns and from 15 to 20 or greater microns in length.

The conductive filler may comprise granules formed from particles of the conductive element or material, as hereinbefore described, coated with a suitable polymer, most preferably an elastomer, such as silicone. Such granules and a compressible material comprising such granules, together with its method of preparation are disclosed in WO 99/38173, the disclosure of which is incorporated herein by reference.

The conductive filler is dispersed within a polymeric matrix, to form the compressible material. Any suitable polymer may be used to form the matrix, provided it meets the requirements of flexibility, strength, compressibility and resilience in order to function in the present invention.

The polymer preferably has the following general properties:

-   -   i) a low surface energy, preferably in -the range of from 15 to         50 dyne/cm, more preferably from 22 to 30 dyne/cm;     -   ii) a surface energy of wetting for hardened polymer higher than         its uncured liquid;     -   iii) a low energy of rotation, to provide a high degree of         flexibility, preferably an energy of rotation close to zero;     -   iv) a high pressure sensitive tack to the filler particles and         electrical contacts to which the material may be attached;     -   v) a position as a positive charge carrier high on the         triboelectric series, that is a low conductivity of negative         charge carriers on its surface;     -   vi) chemically inert, to provide a barrier to the ingress of         oxygen and water or water vapour.

The polymer is preferably an elastomer, most preferably a silicone elastomer. A particularly suitable elastomer is one based on polydimethysiloxane, with leaving groups, cross-linking agents and cure systems based on one of the following systems:

LEAVING GROUP CROSS-LINKING AGENT CURE SYSTEM HOC(O)CH₃ CH₃Si[OC(O)CH₃]₃ Acetic acid HOCH₃ CH₃Si(OCH₃)₃ Alcohol HONC(CH₃)(C₂H₅) CH₃Si[ONC(CH₃)C₂H₅]₃ Oxime NH(CH₃)C(O)C₆H₅ CH₃Si[N(CH₃)C(O)C₆H₅]₃ Benzamide

The elastomer may be a mixture comprising cured elastomers selected from one, two or three component silicones, one, two or more-component polygermanes and polyphosphazines.

The polymer may comprise one or more modifiers, to modify the physical and/or electrical properties of the polymer composition. Suitable modifiers include alkyl and hydroxyalkylcellulose, carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, polyacrylamide, polyethylene glycol, poly(ethylene oxide), polyvinyl alcohol, polyvinylpyrrolidine, starch and its modifications, calcium carbonate, fumed silica, silica gel and silicone analogues.

The compressible material should be sufficiently resilient, so as to return to the relaxed or quiescent state when the applied pressure is released. The polymer composition preferably comprises a modifier, which is selected to provide the required resilient properties and accelerate the elastic return of the composition to the relaxed or quiescent state. A most suitable modifier for improving the elastic return of the material is fumed silica, which may be included in an amount of from 0.01 to 20% by weight of the polymer composition.

The conductive filler is present in the compressible material in a sufficient quantity to provide the required electrical conductivity properties under the pressure to be applied by the foot of the wearer of the shoe. The compressible material may comprise the filler and elastomer in a ratio of from 1:1 to 3:1, more preferably about 7:4.

The compressible material is typically present as a layer extending across the whole or a portion of the sole of the shoe. The thickness of the layer is selected in order to provide the desired electrical response of the compressible material to the pressure applied by the wearer of the shoe during use. This may vary according to the function to be performed by the shoe. Typically, the compressible material will be present in a layer having a thickness of from 0.5 to 3 mm, more preferably from 1 to 2 mm.

If the sole of the shoe comprises a plurality of discrete portions of compressible material, to provide a plurality of separate electrical controls, the composition and properties of the different portions, such as thickness of the layer, may vary according to their location in the shoe, in order to tailor the operation of a given portion to its position, the pressure to be applied by the respective part of the wearer's foot, and the function to be performed.

If a variable level of conductance is required, as opposed to a simple on/off function, the compressible material may be provided with a means to stress the material over a cross-sectional are proportional to the level of conductance required. The techniques to achieve this are described in WO 00179546, the disclosure of which is incorporated herein by reference.

The sole of the shoe will typically comprise the compressible material as a layer within the otherwise conventional construction of the shoe sole. The compressible material is at or sufficiently close-to the surface of the sole to be contacted by the foot of the wearer so as to apply sufficient pressure to the compressible material.

Electrical contacts may be provided to the compressible material in a conventional manner known in the art, in order to electrically connect the compressible material with the other means and devices within the shoe, such as one or more display devices to provide a display on the exterior of the shoe.

In another aspect, the present invention provides an insole for use in a shoe, the insole comprising a compressible material, the material being such that the application of a pressure above a threshold pressure causes the electrical conductivity of the material to change.

The insole may be used to provide a means for controlling the function of one or more electrical devices that may be incorporated into the shoe or may be integral with or mounted on the insole itself.

In a preferred embodiment, the insole comprises an extension member, such that, when installed in a shoe, the extension member extends from the sole of the shoe to the exterior of the shoe. The extension member thus provides a platform for mounting a wide range of electrical devices, such as a pedometer or a wide range of display devices.

The insole may consist of a single layer of the compressible material. Alternatively, the insole may comprise a layer of compressible material disposed between one or more other layers. For example, the compressible material may be incorporated into a laminar structure comprising layers of material to provide such properties as strength and impermeability to water, water vapour or the like to the insole.

The composition and properties of the compressible material included in the insole are as hereinbefore described.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described, by way of example only, having reference to the accompanying drawings, in which:

FIG. 1 is a cross-sectional representation of a portion of the sole or a shoe or an insole according to a first embodiment of the present invention;

FIG. 2 is a plan view of an insole according to a second embodiment of the present invention; and

FIG. 3 is a plan view of an insole according to a:third embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, there is shown a portion of the sole of a shoe or an insole for use in a shoe, generally indicated as 2. The sole comprises a firm and substantially incompressible support layer 4, on which is disposed a layer of compressible QTC (ex Peratech Limited) 6. An optional protective barrier layer 8 to prevent the ingress of moisture from a wearers foot is also shown.

The layer of QTC is connected at either side by conventional wires 10 and 12 to form an electric circuit with a display device 14. In operation, pressure applied to the sole 2, indicated by arrows A, causes the resistivity of the QTC layer 6 to reduce so that the electrical circuit is completed. In this way, the sole 2 responds to pressure applied by the foot of a wearer to activate and/or control the function of the display device.

Referring to FIG. 2, there is shown an insole for a shoe, generally indicated as 102. The insole comprises a heel portion 104, having a disc 106 of QTC (ex Peratech Limited). The insole 102 further comprises an insole extension 108 extending from the heel portion 104 of the insole. A display device 110 is mounted to the free end of the insole extension 108. The insole extension 108 is of sufficient length that the display device 110 is disposed on the exterior surface of the shoe when the insole is properly installed in the shoe. Wires 112 and 114 extend from the disc 106 of QTC along the insole extension 108 to the display device 110. Pressure applied to the disc 106 of QTC is used to activate and control the function of the display device 110, as described hereinbefore with reference to FIG. 1.

An alternative insole arrangement is shown in FIG. 3, which shows an insole for a shoe, generally indicated as 202. The insole comprises a heel portion 204 and a toe portion 206. An insole extension 208 extends from the heel portion 204 of the insole, to the free end of which is mounted a display device 210. The insole extension 208 is of sufficient length that the display device 210 is disposed on the exterior surface of the shoe when the insole is properly installed in the shoe.

A disc 212 of QTC (ex. Peratech Limited) is disposed in the heel portion 204 of the insole 202. A similar disc 214 of QTC is disposed in the insole in a position corresponding to the ball of the foot of the user. Five smaller discs 216 a to 216 e are disposed in the toe portion 206 of the insole. A network of wires 218 extends from the discs 212, 214 and 216 to the display device 210. In operation, each of the discs 212, 214 and 216 may be used to control a function of the display device 210, for example to switch the display on or off, to operate the display or to program the display device with a new display routine. It will be appreciated that the arrangement of discs 212 to 216 in the insole 202 provides a means for activating and controlling a complex display routine on the display device, simply by the application of pressure by the appropriate portion of the users foot within the shoe being worn.

The embodiments shown in the accompanying figures have been described with reference to the use of a compressible material to control a display device mounted on the exterior of the shoe. It will be appreciated that the arrangement of one or more portions of compressible material, such as QTC, within the insole or within the sole of a shoe, may be used to control a wide variety of devices, not limited to display devices, but including devices to provide information about the movement and position of a users foot within their shoe, the number of steps being taken, etc. 

1. A shoe having a sole, at least a portion of the sole of the shoe comprising a compressible material, the material being such that the application of a pressure above a threshold pressure causes the electrical conductivity of the material to change.
 2. A shoe comprising: a sole; a display means operable by the wearer of the shoe to provide a display on the exterior surface of the shoe; wherein the sole of the shoe comprises a compressible material, the material being such that the application of pressure causes the electrical conductivity of the material to change, whereby the display means may be controlled by the application of pressure to the compressible material in the sole of the shoe.
 3. The shoe according to either of claims 1 or 2, wherein the compressible material is non-conducting in the quiescent position and is caused to conduct electricity upon the application of pressure to the compressible material.
 4. The shoe according to claim 3, wherein the compressible material becomes an electrical conductor above a threshold applied pressure.
 5. The shoe according to any preceding claim, wherein the compressible material is a quantum tunneling composite (QTC).
 6. The shoe according to any preceding claim, wherein the compressible material comprises a filler of conductive particles in a polymer matrix.
 7. The shoe according to claim 6, wherein the filler comprises nickel, titanium, zirconium, copper or a mixture thereof.
 8. The shoe according to either of claims 6 or 7, wherein the filler comprises a powder of a conductive element or material.
 9. The shoe according to any of claims 6 to 8, wherein the filler comprises a layer of a conductive element or material on a carrier of powder, grains, fibres or other shaped forms.
 10. The shoe according to any of claims 6 to 9, wherein the filler comprises granules of a conductive element or material.
 11. The shoe according to any of claims 6 to 10, wherein the granules have a diameter of up to 2 mm, more preferably up to 1 mm, especially 0.04 to 0.2 mm.
 12. The shoe according to any of claims 6 to 11, wherein the particles of conductive element or material are dendritic, filamentous or spiked in form.
 13. The shoe according to any of claims 6 to 12, wherein the filler comprises granules of a conductive element or material coated in a polymer, in particular an elastomer.
 14. The shoe according to any of claims 6 to 13, wherein the polymer matrix comprises an elastomer, in particular a silicone elastomer.
 15. The shoe according to any of claims 6 to 14, wherein the compressible material further comprises a modifier to improve the elastic response of the material, in particular fumed silica.
 16. The shoe according to any preceding claim, wherein the compressible material is in a layer having a thickness of from 0.5 to 3 mm, more preferably from 1 to 2 mm.
 17. The shoe according to any preceding, wherein the sole comprises a plurality of discrete portions of compressible material.
 18. The shoe according to claim 17, wherein each of the discrete portions has a different composition and/or property, to tailor the portion to its location with respect to the foot of the wearer of the shoe.
 19. An insole for use in a shoe, the insole comprising a compressible material, the material being such that the application of a pressure above a threshold pressure causes the electrical conductivity of the material to change.
 20. The insole according to claim 19, further comprising a connection to a display device.
 21. The insole according to claim 20, wherein the display device is mounted on an insole extension extending from the insole such that, when the insole is in position in a shoe, the display device provides a display on the exterior of the shoe.
 22. The insole according to any of claims 19 to 21, wherein the compressible material is non-conducting in the quiescent position and is caused to conduct electricity upon the application of pressure to the compressible material.
 23. The insole according to claim 22, wherein the compressible material becomes an electrical conductor above a threshold applied pressure.
 24. The insole according to any of claims 19 to 23, wherein the compressible material is a quantum tunneling composite (QTC).
 25. The insole according to any of claims 19 to 24, wherein the compressible material comprises a filler of conductive particles in a polymer matrix.
 26. The insole according to claim 25, wherein the filler comprises nickel, titanium, zirconium, copper or a mixture thereof.
 27. The insole according to either of claims 25 or 26, wherein the filler comprises a powder of a conductive element or material.
 28. The insole according to any of claims 25 to 27, wherein the filler comprises a layer of a conductive element or material on a carrier of powder, grains, fibres or other shaped forms.
 29. The insole according to any of claims 25 to 28, wherein the filler comprises granules of a conductive element or material.
 30. The insole according to any of claims 25 to 29, wherein the granules have a diameter of up to 2 mm, more preferably up to 1 mm, especially 0.04 to 0.2 mm.
 31. The insole according to any of claims 25 to 30, wherein the particles of conductive element or material are dendritic, filamentous or spiked in form.
 32. The insole according to any of claims 25 to 31, wherein the filler comprises granules of a conductive element or material coated in a polymer, in particular an elastomer.
 33. The insole according to any of claims 25 to 32 wherein the polymer matrix comprises an elastomer, in particular a silicone elastomer.
 34. The insole according to any of claims 25 to 33, wherein the compressible material further comprises a modifier to improve the elastic response of the material, in particular fumed silica.
 35. The insole according to any of claims 19 to 34, wherein the compressible material is in a layer having a thickness of from 0.5 to 3 mm, more preferably from 1 to 2 mm.
 36. The insole according to any of claims 19 to 35, wherein the sole comprises a plurality of discrete portions of compressible material.
 37. The insole according to claim 36, wherein each of the discrete portions has a different composition and/or property, to tailor the portion to its location with respect to the foot of the wearer of the shoe. 